[ncalburt]

It obviously Noro virus .
The water tanks are not probably cleans and filtered .
Never drink anything but bottled water on a cruise .
Those Alaskan cruises are notorious for this noro virus .
The local Alaskan hospitals treat thousand of cruise clients every year .
In Juneau AK the local hospital ambulances are busy at the port. i

[entropy12]

Already did 26 cruises, and 2 or 3 more coming up in 2018.
Never had a single problem on any of the cruises, which included Alaska (4 or 5), Mediterranean (2 weeks), West coast of Mexico (5 or 6), Caribbean (remaining others).

Note that Cruises are required to report outbreaks. Restaurants are not required to report. Incidences in restaurants in US are most likely 1000 times more on cruises from American ports. Myself have experienced intestinal problems many times eating in restaurants. But never on any of the the 26 cruises.